A semiconductor injection laser diode is a body of single crystalline semiconductor material having regions of opposite conductivity type thereby forming a p-n junction. When the diode is properly electrically biased, light is emitted by recombination of oppositely charged carriers in the p-n junction region. Since these laser diodes are low output power devices, arrays of diodes have been connected together to increase the output power. To provide and maintain good optical alignment of the elements of the array with one another and to minimize the assembly required, arrays have been fabricated so that the elements are on a single substrate.
A problem with such arrays is maintaining the relative electrical isolation between the different elements of the array. Lamorte et al, U.S. Pat. No. 3,471,923 issued Dec. 9, 1966, have disclosed an array of laser diodes on a single substrate where the electrical isolation is obtained by cutting slots through the semiconductor body down to the substrate layer. A separate electrical contact is then made to each diode on the side separated by the slots and a common electrical contact is made to the other side of the substrate. This approach has the undesirable feature of requiring the additional step of cutting the slots after the fabrication of the array has been completed, thus increasing cost and decreasing reliability.